1. Field of the Invention
The invention pertains to the field of variable cam timing systems. More particularly, the invention pertains to a variable cam timing system supported by a camshaft bearing journal to provide an engine with shorter axial length.
2. Description of Related Art
The axial length of the engine systems, including the variable cam timing (VCT) phaser has been reduced in the prior art to allow the engine to fit into smaller engine spaces. One example of how the engine length was decreased is U.S. Pat. No. 6,035,817, which discloses an internal combustion engine where the camshaft is supported at one end by a combined bearing and valve body plate that is detachable from the supporting engine body. The variable valve timing (VVT) mechanisms are attached to the valve body plate. By attaching the VVT mechanism to the plate, passages may be added to the plate rather than in the cylinder head casing, the driving sprockets are positioned much closer to the bearing surface formed by the plate, and the overall length is decreased relative to the cylinder head fasteners.
Prior art FIG. 1 shows a conventional variable cam timing system that has not been decreased in length and where the variable cam timing (VCT) mechanism or phaser 12 is located in front of the first camshaft journal bearing 6 of the camshaft 4. A second camshaft journal bearing 8 is shown, and additional bearings may also be present. A solenoid 2 actuates the center mounted spool valve 14 of the VCT phaser 12. Sprocket 10 is mounted to the VCT phaser 12 on the side closest to the first camshaft journal bearing 6.